1. Field of the Invention
The present invention relates to a gray insertion technique of a liquid crystal display, and more particularly, to a gray insertion technique adaptively adjusting charging time of a gray insertion image to adjust gray insertion of various levels.
2. Description of Related Art
The liquid crystal display (LCD) adopts a hold-type display method so when the LCD displays a dynamic image, motion blur may occur. In general, a gray insertion technique is conventionally adopted to reduce motion blur. A brief illustration is first provided below on how the LCD panel is driven.
A driving signal for the LCD panel mainly includes two parts, a data signal provided by a source driver and a scan signal provided by a gate driver. The data signal mainly provides a voltage signal corresponding to each pixel gray level. The scan signal is used to control a switch signal input from a voltage of each row of pixels. The scan signal scans row by row. Generally speaking, each pixel includes a thin film transistor comprising a gate, a source, and a drain. The scan signal is used to control the conduction of the thin film transistor. When the thin film transistor is turned on, the data signal may charge a pixel storage capacitor through the thin film transistor.
FIG. 1A is a schematic view of a scan signal when a conventional LCD panel displays a normal image. Referring to FIG. 1A, when scan signals Gate 01˜Gate N are at logic high levels, the thin film transistor is turned on and the data signal may charge the pixel storage capacitor through the thin film transistor for displaying a normal image.
FIG. 1B is a schematic view of a scan signal when a conventional LCD panel displays a normal image and a gray insertion image. When the gray insertion function is activated, a frame may be divided into two sections, a normal frame 101 and a gray insertion frame 102. In the gray insertion frame 102, the time when the scan signals Gate 01˜Gate N are at logic high levels is fixed.
It should be noted that although the gray insertion technique may improve motion blur of a dynamic image, it may greatly decrease brightness of an image as well. When the LCD displays a static image such as a photograph or text image, motion blur does not occur. If the gray insertion technique is used in the LCD during the display of a static image, it results in low image contrast.
Therefore, when the LCD displays a static image, the gray insertion function is manually turned off in the conventional technology. However, turning on and off the gray insertion function results in significant variance in the brightness level of the display image and hence causes great discomfort to the human eye.